The invention relates to incandescent lamps generally, and with greater particularity to equipment which utilize such lamps to provide light for the production of motion pictures. Such equipment will hereinafter be referred to as "movie lights."
One of the latest developments in the motion picture field has been the "instant movie" system designed by the Polaroid Corporation, Cambridge, Massachusetts. This system includes an automatic-exposure movie camera in which a film-containing cassette is used. Exposure of the film occurs within the cassette which is inserted within a special projector, or "player" and the film projected on the player's screen. Processing of the film requires only about ninety seconds.
The present invention is especially adapted for utilization with the above movie system, in addition to other systems requiring similar levels of illumination. As will be described, the present invention is electrically operated and is fully capable of being mounted on a movie camera such as the above. Understandably, the function of the invention is to substantially uniformly illuminate a subject field located at a prescribed distance in front of the camera during periods of use in which normally satisfactory illumination is not otherwise available.
By uniformly illuminated is meant a corner-to-center illumination ratio within the range of about 0.32 to about 0.45 for a rectangular subject field located at a distance of approximately fifteen feet from the movie camera. That is, the center of the subject field at this distance requires a level of illumination of about two and one-half to three times the level needed for the corners of the field. A typical field is about fifty-eight inches (vertical) by seventy-eight inches (horizontal). A desired luminous intensity at the center of the field is within the range of about 14,500 to 17,000 candelas while that of the respective corners of the field is within the range of about 5,000 to 7,500 candelas.
Most known systems capable of providing the above illumination are relatively expensive to both operate and purchase as well as very awkward to operate when used in conjunction with movie cameras.
It is believed, therefore, that a movie lighting system which is compact, relatively, inexpensive, and capable of providing the above-desired levels of illumination would constitute an advancement in the art. It is further believed that a lamp unit capable of being used in such a system, and a reflector for use with said unit would also constitute advancements in the art.